Gustavo, Contributor posted:
2'. The two products are the same quality. (This is the only one that sounds a bit weird to me.)
Very nice variations, Gustavo. I agree with you that (2') sounds weird. While it is possible to use "of the same quality" (as in (1')) instead, here's what I would say:
(2'') The two products are the same in quality.
With "size," however, even though "are of the same size" and "are the same in size" are possible, native speakers use "are the same size" so frequently that, if nothing else, it must be deemed idiomatically correct. We also see the same type of thing in the extremely common sentence "Pick on someone your own size." While it is possible to say "Pick on someone of your own size," most people don't.